My favorite game, came out when I was 5 and have been playing it ever since. I can't stop faving your CT art, it's very good, you capture the characters well. It's nice to see them in a different style other than an imitation of Toriyama's. Excellent work, Robaato!
I believe the character was named "Marl" in the original Japanese version of the game, so that is most likely the correct pronunciation. Personally, I thought the single E of "Marle" was always silent. The pronunciation "Mar-lee" just doesn't mesh with the spelling. It would be like reading "Marly" or "Marlie".
Anyway, Marle's face turned out great in this pic.
But yeah I only know of one main image that she looks actually tough and that's the main iconic profile art of her. Even in the game, she's clearly a tomboy, but there's also been times where her femininity shows.